Cancers such as lung cancer, colon cancer, breast cancer, prostatic cancer, uterine cancer, choriocarcinoma, bladder cancer, kidney cancer, thyroid cancer, parotid gland cancer, head and neck cancer, brain tumor, bone and soft tissue sarcomas, ureteral cancer, liver cancer, ovarian cancer, fallopian tube cancer, esophagus cancer, and gastric cancer are all malignant tumors and are, particularly if progressive, difficult to treat and often fatal. Thus, the most important challenge as a measure against cancer is the early detection of carcinomas.
Tumor markers such as CEA and CA19-9 have previously been reported and used in the diagnosis of such cancers and the observation of the prognosis. However, each of them has a positive rate on the order of only 20 to 30%, and most markers exhibit negative particularly for early stage cancer. Moreover, outcomes from therapies for advanced cancer are poor as described above, and early detection brings about the greatest effect. Therefore, it has been expected to find a novel and useful tumor marker. For example, those described in JP Patent Publication (Kokai) No. 7-51065A (1995), WO00/060073, and JP Patent Publication (Kohyo) No. 2000-511536A (2000) have been known as molecular biological methods of diagnosis using antigenic protein markers.
The surgical excision of cancer tissues, the systemic administration of anticancer agents, and so on has been performed as cancer therapies. However, these therapies are less effective for cancer that has entered an advanced stage, as described above, and also present the problem of a significant physical burden on patients even if their cancers are found early.